LS Gurus - Need assistance with cam sensor codes

adamk

adamk

Well-Known Member
Joined
Nov 20, 2010
Location
Burlington
Currently battling a no start issue with my LS swapped YJ and it’s all related to the cam sensor.

Back story: started having an intermittent code thrown for reference signal high or low for the cam position sensor. Engine would still start but, at times would be a long crank. In an attempt to solve this problem, I replaced the cam sensor and check the wiring. First crank with the new sensor and it fired up without issue. Went for a quick drive and then shut it down and tried to restart and it wouldn’t start. Long crank and occasional backfire. Started troubleshooting some more and found my battery voltage was a bit low (11.6v). Threw a charger on it and came back later to check voltage at the cam sensor plug and all was good. Plugged it in and fired up without issue. Shut down and went to restart and wouldn’t start. Unplugged and replugged the sensor and fired right up.

So, what do you gurus think I’m battling here? Sensor seems to work after unplugging it and then back in but not when left plugged in constantly. Google says to check reference voltage back to the pcm and it should be 40-60% of the supplied voltage. I currently don’t have a scan tool that will allow me to pull cam sensor data while running.

Thanks in advance!
 
I had an intermittent issue with the cam position sensor on the the LS1 that I swapped into my dad's 55. Long cranking and the occasional backfire. Turns out I had a bent terminal in the plug that would sometimes allow it to make contact with the sensor, and sometimes it was pushing the terminal far enough back in the plug that it wasn't making good contact.

We never had a no start condition related to this issue though. My understanding is that the computer would swap the timing around if the signal was bad for a certain time, and that is why the backfire would occur.
 
Bebop said:
Unplug the cam sensor.
Does it start?

What is the exact code(s) you're getting ?
Click to expand...
Haven’t tried starting with it unplugged but I can do that this afternoon. The two codes I’m getting at P0342 and P0343 which are contradictory to each other.

thecj3man said:
I had an intermittent issue with the cam position sensor on the the LS1 that I swapped into my dad's 55. Long cranking and the occasional backfire. Turns out I had a bent terminal in the plug that would sometimes allow it to make contact with the sensor, and sometimes it was pushing the terminal far enough back in the plug that it wasn't making good contact.

We never had a no start condition related to this issue though. My understanding is that the computer would swap the timing around if the signal was bad for a certain time, and that is why the backfire would occur.
Click to expand...
While I definitely looked at the connector and used my meter to check the wiring, I didn’t really “study” the female pins in the connector and can look that over. Thanks for the experience shared.
 
thecj3man said:
We never had a no start condition related to this issue though. My understanding is that the computer would swap the timing around if the signal was bad for a certain time, and that is why the backfire would occur.
Click to expand...
Exactly why I asked to see if it would start without the sensor plugged in.
PCM will switch to batch fire instead of sequential.

adamk said:
Haven’t tried starting with it unplugged but I can do that this afternoon. The two codes I’m getting at P0342 and P0343 which are contradictory to each other.
Click to expand...
thecj3man said:
Turns out I had a bent terminal in the plug that would sometimes allow it to make contact with the sensor, and sometimes it was pushing the terminal far enough back in the plug that it wasn't making good contact.
Click to expand...
Agreed the description looks like a bad contact.
 
You can take the individual terminals out of the delphi connecter and bend the spring contact back out. Or just buy a new connector pigtail for $10 and try it out.
 
Good news is that it does start with the sensor unplugged but had a long crank and a single back fire. Given this, and what everyone has pointed to thus far, my next steps will be pulling the connector apart and tightening up female pins.

Thanks for everyone's quick response to this. Hopefully it works and I'll report back
 
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